There are no Auto delete bots on bitcointalk, but maybe there should be.
Your thread was thrashed by the mods, that's why you got no notification about the deletion. There is usually a message for replies and threads that are deleted permanently, but if it's thrashed, it can be reversed at a later time, and no deletion notification is sent out.
For reference, here is the deleted
threadI'm writing from a place of hurt.
Mods act on their discretion and reports. Many users here have had a couple of deleted threads and replies, spammers more than others.
Just familiarize yourself with the forum rules more.